Corneal-scleral orthokeratology contact lens

ABSTRACT

A corneal-scleral orthokeratology contact lens is formed of rigid gas permeable material with uniform arc lengths in the treatment area even when the corneal curvature varies and asymmetric blends or splines called minor zones, where the portion of the blend or spline is shorter toward the lens center and broader toward the lens edge, and relieve the treatment area of all centering responsibility, transferring it to the limbal-scleral region. The method of determining the total sagittal height of an eye at a given chord diameter to predetermine exact fitting parameters and predict unaided visual outcome trial lenses, with exact chord and sagittal height values used to match the sagittal height of an eye, the sagittal value may be obtained from some ocular topographers. A computer program can easily take the sagittal information and design an optimum lens.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Patent ApplicationSer. No. 60/634,494 filed Jan. 12, 2005, herein incorporated byreference.

BACKGROUND OF THE INVENTION

This invention relates generally to contact lenses, and moreparticularly to rigid gas permeable corneal-scleral contact lenses forreshaping the cornea of an eye on a temporary basis to treat visualacuity deficiencies, a process known as orthokeratology. The inventionfurther relates to methods of designing and application of such lenses,and means of obtaining key measurements from the eye by the use ofdiagnostic lenses.

SUMMARY OF THE INVENTION

The prior art is replete with innovations in contact lens designs fororthokeratology. All of these designs are by necessity made from rigidcontact lens materials. Soft contact lens material will not exertsufficient localized pressure to alter the shape of the cornea. It isbelieved that all previous orthokeratology designs, patented orotherwise, have been corneal contact lenses, with the exception of onepatent, #No. 5,929,968, which is a corneal-scleral lens. Although themolding contact lens disclosed in this patent is well suited for itsintended purpose, there is a continual need for improvement. Bydefinition, a corneal contact lens is supported entirely by the cornea.Therefore, all functions of the lens must take place on the cornea, suchas vision, corneal orthokeratology treatment, tear exchange, curves forcomfort, curves to center the lens and curves for edge contour. Eachpart of a corneal contact lens has a fitting duty and in the case oforthokeratology, some parts are multifunctional. This is a real problem,compromises must be made in corneal orthokeratology contact lens designswhen, for example, centering, and treatment issues cross-functionallines. Many attempts have been made to address problems of more reliablecentering, dislodging, adherence, faster treatment, lasting treatment,more reliable treatment, and comfort. Although the orthokeratologycorneal contact lens designs produced some amazing results, all of theproblems listed above are still present to some degree and after fiftyyears of designing and tweaking designs of corneal orthokeratologycontact lenses, it could be assumed that these problems are indigenousto corneal lenses. Properly fitted corneal contact lenses are requiredto have some movement with each blink and with eye rotation. In the caseof orthokeratology the movement is highly controlled as noted in Tabband Ballegeer's U.S. Pat. No. 6,582,077 B1 column six (6). The necessityfor movement with corneal contact lenses presents the opportunity forlens decentering, dislodgment, adherence, blurring or shrinking of thetreatment zone, and friction that can compromise comfort.

The present invention is directed to solving the problems set forthabove. It is therefore an object of the invention to have anorthokeratology lens where the centering is completely reliable andindependent of the treatment.

It is also an object of the invention to have an orthokeratology contactlens that has no chance of dislodgement once in place on the eye.

A further object of the invention is to have an orthokeratology lensthat can not adhere to the cornea.

Another object of the invention is that for fast, reliable andcomfortable results, it is also desirable to have specially designedcorneal-scleral lenses that can be used to accurately determine theocular sagittal height at various known ocular cord diameters forprecise lens design purposes, for all corneal-scleral lenses as well asorthokeratology.

In accordance with one aspect of the present invention a corneal-scleralorthokeratology contact lens is formed of a rigid gas permeable materialand has a central posterior treatment surface designed to have the samepredetermined arc length in the treatment area when corneal treatmentcurvatures vary. The use of consistent arc lengths rather than chorddiameter (optical zone) overcomes the deficiencies of the prior art bytreating the same variorum of the epithelium at each corneal curvature.

In another aspect of the invention, a corneal-scleral orthokeratologycontact lens is formed of a rigid gas permeable material havingasymmetric blends, between spherical or aspherical curves where as theblends are wider to the edge side of the zone and more narrow to theinner side. Example: the juncture between 7.0-millimeter zone would be:the outside blend would be 0.4 millimeters (7.4) and the blend on theinside would be 0.2 millimeters (6.8).

The ability to properly treat an eye is greatly increased when theacceleration of flattening of the eye is accommodated by the lensdesign.

In another aspect of the present invention an orthokeratology contactlens formed of a rigid gas permeable material being a corneal-scleralcontact lens, the peripheral portion being adapted to be positioned overthe limbus and scleral portions of the eye and with similar radiicentering the lens from outside the cornea relieving the orthokeratologytreatment area of all centering responsibility.

Still another aspect of the invention is a method of determining thetotal sagittal height of the eye at a given chord diameter topredetermine exact fitting parameters and predict visual outcome. Triallenses with exact chords and sagittal height are placed on the eye andwith the use of fluorocein, the contact lens fitter can observe a threepoint touch pattern when the sagittal height of the lens matches thesagittal height of the eye. It is also possible to extract sagittal andchord information about the eye from some ocular topographer and oncethis information is obtained, simple formulas may be employed for lensdesigns.

In addition to providing an orthokeratology contact lens that providesmore predictable results because of the consistent treatment volume ofthe epithelium cells and controlled scleral-limbal centering and addedcomfort because the lens edges are tucked under the eyelids, as it canbe seen from a study of the above description and its drawing, the lensembodying the present invention, unlike corneal orthokeratology lenses,is particularly beneficial in treating visual acuity deficiencies bybeing used as a retainer lens in a flexible wear schedule. It is notrequired to be worn just at night. The lens can be worn during the dayfor a few hours, removed and provide the subject with functional unaidedvision for several hours.

Alternatively, the lens can be worn as a standard daily wear contactlens and simply have good functional unaided vision when the lens isremoved.

A further alternative is that the lens could be worn sporadically ifdesired. Once the fit is obtained it would not change for at least ayear and the comfort is such that there is virtually no adaptation time.

In summary there is taught a corneal-scleral orthokeratology contactlens formed of rigid gas permeable material with uniform arc lengths inthe treatment area even when the corneal curvature varies and asymmetricblends or splines, sometimes referred to as minor zones, formed on theposterior surface of the lens. The portion of the blend or spline isshorter toward the lens center and broader toward the lens edge. Thedesign will relieve the treatment area of the lens of all centeringresponsibility, transferring centering responsibility to thelimbal-scleral region so the treatment area can be designed to treatwithout concern of centering.

The method of determining the total sagittal height of an eye at a givenchord diameter to predetermine exact fitting parameters and predictunaided visual outcome trial lenses, with exact chord and sagittalheight values used to match the sagittal height of an eye, is alsotaught herein.

The sagittal value may be obtained from some ocular topographers. Acomputer program can easily take the sagittal information and design anoptimum lens that has comfort that a corneal orthokeratology lens cannot deliver, while providing greater unaided visual accuracy and longerholding time. With this design the lens will not dislodge and may beworn as an everyday contact lens.

The above summary does not include an exhaustive list of all aspects ofthe present invention. Indeed, the inventor contemplates that hisinvention includes all systems and methods that can be practiced fromall suitable combinations of the various aspects summarized above, aswell as those disclosed in the detailed description below andparticularly pointed out in the claims filed with the application. Suchcombinations have particular advantages not specifically recited in theabove summary.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention can be derived byreferring to the detailed description when considered in connection withthe following illustrative figures. Additionally, all included figuresare non-limiting illustrations of the exemplary embodiment and modes,which similarly avail themselves to any equivalent modes or embodimentsthat are known or obvious to those of reasonable skill in the art.

FIG. 1 is a frontal view of the preferred embodiment of thecorneal-scleral orthokeratology contact lens embodying the presentinvention;

FIG. 2 is a cross-sectional view of the orthokeratology contact lensembodying the present invention in FIG. 1;

FIG. 3 is a frontal view of the preferred embodiment of thecorneal-scleral orthokeratology contact lens embodying the presentinvention, showing the lens in a normal wearing position over thecornea, limbus, and a small portion of the sclera of the eye;

FIG. 4 is a cross-sectional view of the frontal portion of an eyeshowing the preferred embodiment of the corneal-scleral orthokeratologycontact lens embodying the present invention in the normal wearingposition over the cornea, limbus, and a small portion of the sclera ofthe eye;

FIG. 5 is a cross-sectional view of the central treatment zone of thecorneal-scleral orthokeratology contact lens embodying the presentinvention where the arc lengths are the same and the radius and chordlengths differ;

FIG. 6 is a cross-sectional view of the central treatment zone in FIG. 5where the arcs have been flattened, demonstrating their length are thesame;

FIG. 7 is a cross-sectional view of the frontal portion of an eyeshowing the preferred embodiment of a corneal-scleral contact lenshaving a predetermined chord length and sagittal height used to matchthe sagittal height of the eye;

FIG. 8 is a frontal view a portion of an eye showing the preferredembodiment of a corneal-scleral contact lens having a predeterminedchord length and sagittal height matching the sagittal height of theeye.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In this specification and in the claims which follow, reference will bemade to a number of terms which shall be defined to have the followingmeanings: The terms “comprise”, “comprises”, “comprising”, “having”,“including”, “includes” or any variation thereof, are intended toreference a non-exclusive inclusion, such that a process, method,article, composition or apparatus that comprises a list of elements doesnot include only those elements recited, but may also include otherelements not expressly listed and equivalents inherently known orobvious to those of reasonable skill in the art. Other combinationsand/or modifications of structures, arrangements, applications,proportions, elements, materials or components used in the practice ofthe instant invention, in addition to those not specifically recited,may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the scope of the instantinvention and are intended to be included in this disclosure.

Moreover, unless specifically noted, it is the inventors' intent thatthe words and phrases in the specification and the claims be given thecommonly accepted generic meaning or an ordinary and accustomed meaningused by those of ordinary skill in the applicable arts. In the instancewhere these meanings differ, the words and phrases in the specificationand the claims should be given the broadest possible, generic meaning.If it is intended to limit or narrow these meanings specific,descriptive adjectives will be used. Absent the use of these specificadjectives, the words and phrases in the specification and the claimsshould be given the broadest possible, generic meaning. If any otherspecial meaning is intended for any word or phrase, the specificationwill clearly state and define the special meaning.

The use of the words “function,” “means,” or “step” in the specificationor claims is not intended to invoke the special provisions of 35 U.S.C.112, Paragraph 6, to define the invention(s). To the contrary, if theprovisions of 35 U.C.C. 112, Paragraph 6 are intended to be invoked todefine the invention(s), then the claims will specifically state thephrases “means for” or “step for” and a function, without recitation insuch phrases of any material, structure, or at in support of thefunction. Contrastingly, the intention is NOT to invoke the provisionsof 35 U.S.C. 112, Paragraph 6 when the claims recite a “means for” or a“step for” performing a function with recitation of any structure,material, or act in support of the function. If the provisions of 35U.S.C. 112, Paragraph 6 are invoked to define the invention(s) it isintended that the inventions not be limited only to the specificstructure, materials, or acts that are described in the preferredembodiments, but in addition to include any and all structures,materials, or acts that perform the claimed function, along with any andall known or later-developed equivalent materials, structures, or actsfor performing the claimed function.

Throughout this document, various exemplary embodiments and the bestmodes, known to the inventors at this time, of the invention aredisclosed. These embodiments and modes are not intended to limit thescope, applicability, or configuration or the invention in any way.Rather, the following disclosure is intended to teach both theimplementation of the exemplary embodiments and modes and any equivalentmodes or embodiments that are known or obvious to those of reasonableskill in the art. Additionally, all included figures are non-limitingillustrations of the exemplary embodiments and modes, which similarlyavail themselves to any equivalent modes or embodiments that are knownor obvious to those of reasonable skill in the art.

Referring first to FIGS. 1, 2 and 3 there is shown a corneal-scleralorthokeratology contact lens 10 embodying the principle of the presentinvention. The lens 10 extends over both the cornea 105 and a contiguousportion of the sclera 107 of the eye, and is constructed of a rigid gaspermeable (RGP) material, which will allow the cornea 105 to breath(meaning the exchange of oxygen and carbon dioxide). The orthokeratologycontact lens 10 has ocular bearing areas on the limbus, a small portionof the sclera 107, and selected areas of the cornea 105 so that when theeyelid (not shown) is moved across the lens 10, such as by blinking, theeyelid bearing pressure is controllably distributed over the scleral 107and the corneal portions of the eye 101.

By selective arrangement of the curvatures of the posterior surface 16of the lens 10 and the ocular bearing areas, as described below ingreater detail, the eye lid bearing pressure can be advantageously usedto controllably alter the predefined shape of the cornea.

In the preferred embodiment of the present invention, as shown in FIG. 1through FIG. 4, the posterior surface 16 of the orthokeratologycorneal-scleral contact lens 10 is defined by six concentricallydisposed ocular zones 18-28 and five minor ocular zones 32-40 which areasymmetric blends connecting the six major zones where the inwardposition of the blend is less than the outward portion. The outermostmajor zone 18 and the outermost minor zone 32 are disposed over thescleral portion of the eye and are referred to herein as the scleralzones and have radial widths of from about 0.1 millimeter to about 1.0millimeters which provides a stable, load distributing, scleral footingfor the lens 10. In the lens 10 embodying the present invention, thenext zone inwardly from the scleral minor zone 32 is approximatelyaligned with the limbus 107 of the eye, i.e., the border that is clearlydefined between the cornea and the sclera of the eye, and fordescriptive purposes will be referred to herein as the limbic zone. Thenext major zone inwardly from the limbic zone is positioned near theouter edge of the cornea and is identified herein as theperipheral-corneal zone 20. The curvature of the peripheral-corneal zone20 is key to the overall fit of the lens. It is this curve that iseither steeper or flatter to match the overall sagittal height of theeye at the desired ocular chord diameter. The next zone inwardly fromthe peripheral corneal zone 20 is the next major mid corneal zone 22which will be referred to herein as the mid corneal zone 22.

Peripheral-corneal zone 20, minor zone 34 and mid-corneal zone 22 workin concert to vault the cornea slightly to give a place for tears topool. At the apex of the vault the lens is fenestrated 70 to balance thepressure from the anterior and posterior surfaces to prevent adhesion.The size of the fenestration 70 is between 0.2 millimeters and 1.0millimeters.

The next most inward zone is minor zone 36 which connects zone 22 to thenext major zone 24, which is the first treatment zone exerting a smallamount of pressure on the underlying corneal epithiums. The next mostinward zone is the minor zone 38 connecting the first treatment zone andzone 26. The curvature of zone 26 is varied steeper or flatter to matchthe sagittal height of the cornea in its final treated state. And thenext most inward minor zone 40 connects the treatment zone sagittaladjustment curve with the second treatment curve 28. The curve of thesecond treatment zone 28 is nothing new, it has been done for over fiftyyears. Simply add the sphere component of the refraction to the flat “K”reading. If desired an additional −0.50 D or −0.75 D may be added.

Referring to FIG. 5 and FIG. 6 there is shown the treatment area of thecorneal-scleral orthokeratology contact lens 10 embodying one of theprinciples of the present invention. In the preferred embodiment of thepresent invention, the arc length of the treatment zone is held constantas the curvature of the eye changes. This method maintains a very closerelationship to the same area of treatment regardless of the curvatureof the eye, giving addition accuracy to the overall process for steepand flat eyes.

Referring to FIGS. 7 and 8 there is shown a non-orthokeratologycorneal-scleral contact lens with a predetermined chord length andsagittal height being used to match the sagittal height of the eye bythe use of a touch pattern. The touch spots 50 and 52 with a vault 54between 50 and 52 indicates a match with the eye.

It can be appreciated from the above description that in one embodimentof the invention a corneal-scleral orthokeratology contact lens isformed of rigid gas permeable material having the central posteriortreatment surface (base curve) predetermined to have the same arc lengthfor each corrective base curve required to satisfy each visualcorrection and corneal curvature presented by the human eye, a secondportion not related to the treatment of orthokeratology, which extendsover the peripheral cornea, limbus and a small portion of the scleralsurface of the eye, to relieve the treatment area of all lens centeringresponsibility, a third aspect is minor zones which are asymmetricblends connecting the major curves where the inward most portion of eachblend is less then the outward portion.

The contact lens, as set forth above, may have three major zones fororthokeratology treatment, two for treatment, and a third for thecontrol of the sagittal height of the overall treatment area.

The contact lens, as set forth above, may have three major edge zones,the outer most to align with a small portion of the sclera and thelimbus to center the lens, the next inward curve controls the overallsagittal height of the lens, and the third vaults the peripheral corneafor tear exchange.

Furthermore, and as taught above, another embodiment of the invention isa corneal-scleral diagnostic set of contact lenses formed of a rigidcontact lens material each lens having a predetermined sagittal heightand chord diameter, one of which will match the sagittal height ofalmost any eye. The determination is made by employing a three touchspot pattern where the peripheral curve of the lens touches the scleral360°, and the center of the lens touches the central cornea.

A resulting contact lens design may use the sagittal height informationobtained from the diagnostic fitting set forth above.

The contact lens may be any design corneal-scleral contact lens.

While the invention is described herein in terms of preferredembodiments and generally associated methods, the inventor contemplatesthat alterations and permutations of the preferred embodiments andmethods will become apparent to those skilled in the art upon a readingof the specification and a study of the drawings. Below is a listing ofsome examples of variations contemplated by the inventor and fallingwithin the scope of the claims unless excluded by specific claimlanguage.

Accordingly, neither the above description of preferred exemplaryembodiments nor the abstract defines or constrains the invention.Rather, the issued claims variously define the invention. Each variationof the invention is limited only by the recited limitations of itsrespective claim, and equivalents thereof, without limitation by otherterms not present in the claim.

1. A rigid gas permeable corneal-scleral orthokeratology contact lens,comprising: a) a treatment zone of the lens having a central posteriortreatment surface having a predetermined constant arc length consistentfor different chord lengths of corrective base curves of the treatmentzone b) a second portion of the corneal-scleral orthokeratology contactlens extending over the peripheral cornea, the limbus and a smallportion of the scleral surface of an eye, whereby lens centering isrelieved from the treatment zone of rigid gas permeable corneal-scleralorthokeratology contact lenses.
 2. The invention in accordance withclaim 1 wherein the second portion of the contact lens transfers lenscentering responsibility from a central posterior treatment surface areaof the contact lens to the scleral surface of the eye.
 3. The inventionin accordance with claim 1 comprising a zone of asymmetric blendsconnecting the base curves wherein the inward most portion of each blendis less then the outward portion.
 4. The invention in accordance withclaim 1 comprising major zones, more than one of which major zones isused for providing orthokeratology treatment when said corneal-scleralorthokeratology contact lens is positioned on an eye of the wearer ofthe lens.
 5. The invention in accordance with claim 4 wherein two of themajor zones are for treatment, and a third of said major zones is usedfor the control of the sagittal height of the overall treatment area ofthe eye.
 6. The invention in accordance with claim 1 wherein thecorneal-scleral orthokeratology contact lens further comprises threemajor edge zones, a first of the edge zones being an outer most edgezone to align with a portion of the sclera and the limbus to center thelens.
 7. The invention in accordance with claim 6 wherein thecorneal-scleral orthokeratology contact lens further comprises an inwardcurve for control of the overall sagittal height of the lens.
 8. Theinvention in accordance with claim 6 wherein the corneal-scleralorthokeratology contact lens comprises a major edge zone that vaults theperipheral cornea.
 9. The invention in accordance with claim 1 whereinthe corneal-scleral orthokeratology contact lens comprises; a first edgezone being an outermost edge zone to align with a small portion of thesciera and the limbus to center the lens; a second major edge zonehaving an inward curve controlling the overall sagittal height of thelens; and a third major edge zone vaulting the peripheral cornea. 10.The invention in accordance with claim 1 wherein the central posteriortreatment surface has substantially the same arc length for eachdifferent corrective base curve experienced as the eye adjusts tocorrection as a result of wearing the lens.
 11. The invention inaccordance with claim 10 wherein the central posterior treatment surfacewith substantially the same arc length for each different correctivebase curve experienced as the eye adjusts to correction resulting fromeye lid bearing pressure being advantageously used to controllably alterthe predefined shape of the cornea.